The skin is the largest organ of humans. It has to fulfill a plurality of vital functions, for example, the regulation of heat, and the barrier function against drying of the skin and the entire organism. It also has to act as a protective mechanism against penetration and absorption of extrinsic substances. This barrier function is realized by the epidermis which forms as outermost layer the actual protective cover against the environment. With about one tenth of the total thickness, it is at the same time the thinnest layer of the skin.
The skin is subjected to a plurality of physical, chemical, and biological stresses. A plurality of these stresses lead—for different reasons—to a temporary or permanent redness of the skin. These stresses include, for example, inflammations of the skin, skin reactions, dermographism, soreness of the skin (for example, from dermatitis or contact dermatitis, such as diaper rash), creeping eruption, erysipelas, herpes zoster, frostbite, diphtheria, liver cirrhosis, gout, burns, or allergic reactions.
A special form of skin redness is rosacea. Rosecea [lat. rosaceus >rose-colored<], also known as facial telangiectasis, copper nose, or brandy face, is a chronic disease of the facial skin that occurs in most cases only in middle and older ages and affects in particular the region of the nose, and also the forehead and cheeks (butterfly rash). The dilation of the surface vessels of the skin leads in part to deep red accumulations of blood, dilated vessels (telangiectasias), depending on the form, also to scaling of the skin, gradual formation of papules or pustules, and later (in most cases only in men) to the formation of a rhinophyma. Suspected causes include instability of the vasomotor nerves with a seborrhoeic constitution, endocrine disorders, chronic gastrointestinal diseases, and focal infections; there possibly exists a genetic disposition. Alcohol abuse can likewise be of importance. Treatment occurs locally with antibiotics (Source: Brockhaus—Die Enzyklopaedie: 24 volumes. 20th revised edition. Leipzig, Mannheim: F. A. Brockhaus 1996-99).
Skin rednesses in general and rosacea in particular present great physical and psychological stress to the affected person. Likewise, a viewer sees them in most cases as optically little attractive, sickly, and in-aesthetic.